Integrative descriptions of two new Macrobiotus species (Tardigrada, Eutardigrada, Macrobiotidae) from Mississippi (USA) and Crete (Greece)

Abstract

In this paper, we describe two new Macrobiotus species from Mississippi (USA) and Crete (Greece) by means of integrative taxonomy. Detailed morphological data from light and scanning electron microscopy, as well as molecular data (sequences of four genetic markers: 18S rRNA, 28S rRNA, ITS-2 and COI), are provided in support of the descriptions of the new species. Macrobiotus annewintersaesp. nov. from Mississippi belongs to the Macrobiotus persimilis complex (Macrobiotus clade B) and exhibits a unique egg processes morphology, similar only to Macrobiotus anemone Meyer, Domingue & Hinton, 2014, but mainly differs from that species by the presence of eyes, granulation on all legs, dentate lunulae on legs IV, and of bubble-like structures within the tentacular arms that are present on the distal portion of the egg processes. Macrobiotus rybakisp. nov. from Crete belongs to the Macrobiotus clade A and is most similar to Macrobiotus dariae Pilato & Bertolani, 2004, Macrobiotus noemiae Roszkowska & Kaczmarek, 2019, Macrobiotus santoroi Pilato & D’Urso, 1976, and Macrobiotus serratus Bertolani, Guidi & Rebecchi, 1996, but differs from them mainly in the morphological details of its egg processes and chorion reticulation, but also by a number of morphometric characters. In light of the specific morphology of the egg processes of Macrobiotus annewintersaesp. nov. and Macrobiotus anemone, that are equipped with tentacular arms instead of proper terminal disc, we also provide an updated definition of the Macrobiotus persimilis complex.

Integrative taxonomy reveals new, widely distributed tardigrade species of the genus Paramacrobiotus (Eutardigrada: Macrobiotidae)

“…The data set was compiled from taxa/specimens for which DNA sequences of at least two (out of all four commonly used 18S rRNA, 28S rRNA, ITS-2, COI) molecular markers are available and suitable for concatenation (Table 1 ). The DNA sequences of Macrobiotus rybaki Vecchi & Stec, 2021 38 and Sisusbiotus spectabilis Thulin, 1928 39 , and Mesobiotus datanlanicus Stec, 2019 40 were used as the outgroup. The sequences were aligned using the AUTO method (for COI and ITS2) and the Q-INS-I method (for ribosomal markers: 18S rRNA and 28S rRNA) of MAFFT version 7 41 , 42 and manually checked against non-conservative alignments in BioEdit.…”

Ecology explains anhydrobiotic performance across tardigrades, but the shared evolutionary history matters more

“…On the one hand, some taxa had similar overall survival rates but very different recovery times (e.g. M. annewintersae Vecchi & Stec, 2021 and M. vladimiri Bertolani et al., 2011 both had 88% survival, but the former took an average of 4.4 h to recover, while the latter—only 1.7 h; Table S4; Figure S1. On the other hand, some species had similar recovery times but vastly different survival rates (e.g.…”

Reaching the Monophyly: Re-Evaluation of the Enigmatic Species Tenuibiotus hyperonyx (Maucci, 1983) and the Genus Tenuibiotus (Eutardigrada)

“…The phylum comprises almost 1400 species; however, the real number of taxa that can be recognized in this group seems much higher, as each year brings dozens of new species that are being described and formally named [2][3][4]. Over the last ten years, the implementation of molecular techniques and taxonomic analyses by means of an integrative approach have accelerated the emergence of new species being characterized morphologically and genetically in detail, e.g., [5][6][7][8][9][10][11][12]. The acquisition and accumulation of genetic data tightly associated with phenotypic information enhanced studies on two major subjects in tardigrade taxonomy: (i) The recognition and disentanglement of cryptic/pseudocryptic diversity, e.g., [13][14][15][16][17][18][19] and (ii) the construction of comprehensive molecular phylogenies at the family level or higher that considerably impacted tardigrade systematics, e.g., [20][21][22][23][24][25][26][27][28][29][30].…”